


Family Tradition

by formalizing



Series: Tumblr Writing [21]
Category: Supernatural
Genre: Incest Kink, M/M, Past Underage, Season/Series 12, Sex in a Car, Sibling Incest
Language: English
Status: Completed
Published: 2018-07-02
Updated: 2018-07-02
Packaged: 2019-06-06 01:36:55
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 679
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15183860
Author URL: https://archiveofourown.org/users/formalizing/pseuds/formalizing
Summary: Sam is maybe a bit competitive about whether he or his mother has a greater claim to Baby's backseat.





	Family Tradition

**Author's Note:**

> Originally posted [on Tumblr](http://all-these-formalities.tumblr.com/post/175492733774/early-s12-after-dean-sees-mary-eyeing-the-impalas).

He probably could’ve picked a better time to tell Sam about the moment with mom at the car than when Sam’s riding his dick in that very backseat.

But good sex tends to loosen his tongue, and there’s just nothing better than the way Sam goes for it when they’ve had to wait too long--all single-minded focus and the bruising grip of his fingers on Dean’s shoulders, hot, shuddering breaths as he presses close, making the most of the limited space they have to get exactly what he wants.

Dean also probably could’ve worded it better than, “Pretty sure I was conceived back here.”

And maybe, when Sam stopped short halfway down his cock, open-mouthed and staring at him in vague confusion and disbelief, he didn’t need to breathlessly add, “You too, if the look on mom’s face was anything to go by.”

He’s not sure what reaction he’s expecting--laughter, annoyance, the same shocked expression he’d worn himself when faced with the undeniable realization that their sainted mother had enjoyed more than a few tumbles in Baby’s backseat (should’ve been obvious, maybe, but there’d never been anything about that in dad’s stories)--but he definitely figures it’ll be a mood-killer.

The last thing he expects is for Sam to breathe, “Oh, _fuck_ ,” like he does when Dean’s dirty-talkin’ him to the finish line, eyes fluttering closed and nails digging into skin as he drives himself the rest of the way down onto Dean’s dick.

“Really?” Dean groans, arching up into it, because even if it’s unexpected, he’s definitely not opposed to following-through with this turn of events. “That’s doin’ it for you?”

Sam chuckles under his breath, lifting his hips only to drop heavy back into Dean’s lap, grinding down in small circles like he’s trying to take him impossibly deeper.

“Like it doesn’t do anything for you? I mean, think about it. How many times d’you think you’ve had me in the backseat of what used to be their car?”

Dean doesn’t answer, too distracted by the drag of Sam’s hole around him as he moves again, definitely under-prepped in their enthusiasm and almost unbearably tight for it. Sam doesn’t wait for a response anyway.

“Dozens, and that’s-- _unh, god_ \--that’s a conservative estimate. I’ll bet I’ve spent more time on my back in here than mom ever did.”

Sam’s hips slow as he leans in and brings their lips together just as languidly, starts at the corner of Dean’s mouth and works his way deeper, until he’s licking his way in behind teeth.

“More time spreading my legs for you,” he murmurs, digging his knees into the old familiar leather and his nails into Dean’s skin; possessive. “ _Begging_ for you right here--right where they made us.”

Dean’s not exactly proud of how hard Sam’s hitting buttons he didn’t even know he had, but he doesn’t let that stop him from dropping his hands from Sam’s waist to his ass, getting a firm hold and pulling him up high enough that he has room to fuck him properly. Sam doesn’t protest, lets Dean take the lead with just a stuttered moan against his lips at the change of pace, moving one hand to grab the back of the seat for stability and resting his sweat-slick forehead against Dean’s own.

“Still gonna pretend you don’t get off on it?” he murmurs when Dean’s hips starts to lose their rhythm, clenching like he wasn’t tight enough already as he leans up to press his lips against Dean’s ear. “Fucking your little brother right under mom and dad’s noses. Y’know, it’s almost like we’re doing it in their bed.”

Dean’s barely holding on when Sam kisses his way down Dean’s jaw, pulls back with a breathless grin that bares his teeth.

“Bet she wasn’t a _virgin_ the first time dad took her to the backseat, though. That one’s just for us.”

Dean curses as Sam tips him over the edge, pulling him in with a hand in his hair to kiss that smug smirk right off his face.


End file.
